This is a continuation-in-part of application Ser. No. 09/683,072, filed Nov. 15, 2001, now abandoned.
1. Field of the Invention
The present invention relates to a system for providing compressed and chilled air to an internal combustion engine, while minimizing the attendant fuel consumption penalty.
2. Disclosure Information
In their efforts to provide engines with higher specific output, automotive designers in particular have a devised a veritable plethora of systems for increasing the amount of air and, concomitantly, fuel supplied to reciprocating internal combustion engines. The concept of boosting charge, either with a turbocharger or supercharger, is old and well known. Moreover, the concept of using intercooling between a booster device, such as the turbocharger or supercharger, and the engine is also well known. The present invention, however, provides a system in which two intercoolers are used to achieve maximum charge cooling and densification, while at the same time avoiding an excessive fuel economy penalty. The present system is advantageous because following boosting, charge air enters a first air-to-air heat exchanger wherein heat within the incoming charge air is removed, with the extracted heat being exhausted to the ambient, and with the charge air then flowing to a second intercooler which is liquid cooled. In this manner, it is possible for very high specific output to be achieved with an engine.
An engine having a charge air conditioning system includes a charge booster, a first intercooler for transferring heat from charge air flowing from the booster, with the first intercooler transferring heat from the charge air to ambient, and a second intercooler downstream from the first intercooler for transferring heat from the charge air to a refrigerated fluid. The charge booster may comprise either an engine driven supercharger or a turbocharger driven by exhaust gases from the engine, and yet other types of charge boosters known to those skilled in the art and suggested by this disclosure.
The second intercooler of the present system transfers heat from the charge air to a liquid which may be cooled by a refrigeration system powered by the engine. If desired, the second intercooler may transfer heat from the charge air to a refrigerant flowing through the second intercooler so as to change the state of at least a portion of the refrigerant from a liquid to a gas. The refrigerant system may be used to cool both the passenger compartment of a vehicle and the second intercooler. The refrigerant may comprise common compounds, such as R134a or any of the other compounds commonly employed as working fluids in automotive air conditioning systems. The supply of refrigerant to the second intercooler is controlled by an electronic engine controller in response to a plurality of engine operating parameters such as throttle position, and the rate of change of throttle position, ambient temperature, air charge temperature, and other parameters known to those skilled in the art and suggested by this disclosure.
The second intercooler may also be cooled by an air-to-air heat exchanger as well, in combination with a liquid-to-liquid heat exchanger cooled by the air conditioning system. In this case, the working fluid provided to the second heat exchanger will not be refrigerant but rather fluid such as engine coolant commonly comprised of anti-freeze and water.
According to another aspect of the present invention, a method for conditioning charge air for an automotive internal combustion engine includes the steps of compressing the air with a charge booster, removing heat from the compressed charge air by means of a charge air-to-ambient air heat exchanger, and removing additional heat from the charge air by means of a charge air-to-liquid heat exchanger.
It is an advantage of the present charge air conditioning system that an engine having this system may be operated on gaseous hydrogen with a power output equivalent to that of a comparably sized gasoline fueled engine, but with exhaust emissions approaching a zero level.